Sigma's 120-300mm F2.8 DG OS HSM is the lens to get if a 70-200mm f/2.8 just isn't long enough, but you'll need a strong back to lug it.

The Sigma 120-300mm F2.8 DG OS HSM ($3,599 direct) isn't a lens for the faint of heart. The zoom, which is compatible with full-frame and APS-C camera bodies and is available in Canon, Nikon, and Sigma mounts, brings new meanings to the words big and heavy. But that's the price you pay if you're shooting sports or wildlife and you want the versatility of a zoom and the light-gathering capabilities of an f/2.8 lens. Most event shooters and weekend warriors will be happy with the reach that a comparatively small 70-200mm f/2.8 lens provides, but if you need the extra reach, the image quality that this zoom captures will not disappoint you. It's unique in that it's the only zoom on the market that reaches 300mm at f/2.8. More importantly, it's an impressive performer in terms of sharpness, which earns it our Editors' Choice award.

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It measures 11.5 by 4.8 inches (HD) and weighs 7.5 pounds. If you add the included reversible hood the height increases to 16 inches. Despite the added size, we recommend using the hood for a couple of reasons. It will reduce the chance of lens flares and give a slight boost to image contrast, but more importantly it will go a long way in protecting the huge front element. The hood is made of metal and can take some abuse, and it's certain to prevent stray fingerprints from hitting the lens element. Buying a good multicoated UV filter to protect the lens is a daunting prospect; at 105mm, even the bargain-basement filters can run $50, and a good one will set you back $180. There's no drop-in filter option, so if you're someone who still uses glass filters (the most useful of which are polarizing filters on digital bodies), you'll want to budget for one that fits the lens. You'll also have to reverse or remove the hood if you opt for a polarizing filter; you won't be changing its position very easily with the hood attached.

A tripod collar is included, and that's a good thing. You don't want to put this lens on the front of your SLR and for your mount to bear the brunt of the weight. There are three tripod sockets on the collar, so you can attach a quick release plate and an attachment for a BlackRapid or similar strap system. If you need to move about with this lens, we really recommend that you add a good monopod like the excellent Manfrotto 694CX Carbon Fiber 4-Section Monopod to your kit. Your arms will thank you at the end of a long day of shooting, and you'll be able to get sharp photos at longer shutter speeds. The lens does have built-in optical stabilization, and I was quite happy with its performance in conjunction with a monopod. I managed to get sharp photos at 300mm f/2.8 at shutter speeds as low as 1/60-second when shooting subjects that were relatively still. Obviously you'll want a shorter shutter speed to capture action when the light allows for it.

There are a few control switches on the lens, near the mount. You get a standard autofocus/manual focus toggle swtich, and three-position focus limiter that lets you seek focus over the full range, from 10 meters to infinity, or from the minimum focus distance to 10 meters. The minimum focus distance changes depending on focal length; at 120mm it is 1.5 meters, and at 300mm it is 2.5 meters. There's also a switch to set the stabilization mode, or to disable stabilization, and a custom settings switch. This has an off position and two separate custom settings; you can change custom settings by connecting the lens to your PC via Sigma's USB Dock accessory.

I used Imatest to check the sharpness and distortion of the lens when paired with the full-frame Canon EOS 6D. We consider a lens sharp if it exceeds 1,800 lines per picture height using a center-weighted testing method. The 120-300mm exceeds that mark at eevery tested focal length, even at its maximum f/2.8 aperture. At 120mm f/2.8 it notches 2,415 lines; stopping down progressively increases sharpness, which peaks at 2,657 lines at f/5.6. Edge sharpness is impressive as well. At f/2.8 edges are a little softer than the center, notching 2,143 lines, but are still very impressive. But setting the lens at f/4, f/5.6, or f/8 gives you an image that is evenly sharp from edge to edge. Distortion is completely negligible, just 0.1 percent.

Performance at 200mm is equally impressive. The lens notches 2,351 lines at f/2.8 lines, with edges that are just shy of 1,900 lines. You don't get the even edge-to-edge performance at this focal length that you do at 120mm when you stop down, but the already sharp lens improves steadily as you narrow its aperture, peaking at 2,609 lines at f/8. There's about 0.9 percent pincushion distortion, which is essentially irrelevant in field conditions.

The lens is at its weakest at 300mm, but even there it's pretty darned good. It manages 2,054 lines at f/2.8, with edges that top 1,800 lines. Performance increases as you stop down, peaking at 2,304 lines at f/8; edges top 2,000 lines there. We weren't able to measure distortion at this setting; the bars in our test chart that are used to analyze that weren't able to fit into the frame, but an eyeball inspection shows that it's nothing to be concerned about.

If a 70-200mm isn't long enough, and you need a lens that opens up to f/2.8, the Sigma 120-300mm F2.8 DG OS HSM is a tough one to beat. It's impressively sharp throughout its zoom range, gathers a heck of a lot of light, is compatible with Sigma's USB Dock, and is built like a tank. It's also as big and heavy as a tank, so you'll be a happier photographer if you pair it with a monopod or tripod; thankfully the included tripod collar has three tripod threads so you can move it from a BlackRapid strap to a monopod or tripod with ease. It's not an inexpensive lens, and if you prefer to use a filter to protect your lenses you'll be greeted with some sticker shock when you see the price of a good 105mm filter. Most event shooters will be content with a 70-200mm, but if you're a sports shooter, wildlife photographer, or just someone who really loves telephoto photography you won't be disappointed with the sharpness delivered by this 120-300mm. Its performance earns it our Editors' Choice award, but if you hurt your back schlepping it around, please don't send us your chiropractic bills.

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About the Author

Senior digital camera analyst for the PCMag consumer electronics reviews team, Jim Fisher is a graduate of the Rensselaer Polytechnic Institute, where he concentrated on documentary video production. Jim's interest in photography really took off when he borrowed his father's Hasselblad 500C and light meter in 2007. He honed his writing skills at re... See Full Bio

Sigma 120-300mm F2.8 DG OS HSM

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